#include <stdio.h>

#define Print1 1      // 0001
#define Print2 (1<<1) // 0010
#define Print3 (1<<2) // 0100
#define Print4 (1<<3) // 1000

void Print(int flags)
{
    if(flags & Print1) printf("hello 1\n");
    if(flags & Print2) printf("hello 2\n");
    if(flags & Print3) printf("hello 3\n");
    if(flags & Print4) printf("hello 4\n");
}

int main()
{
    Print(Print1);
    Print(Print1 | Print2);
    Print(Print1 | Print2 | Print3);
    Print(Print3 | Print4);
    Print(Print4);
    return 0;
}